<option value="{{timezone.value}}" *ngFor="let timezone of timezones.success">`

<div class="form-group">
   <select class="form-control" formControlName="timezone" name="timezone" *ngIf="timezones">
            <option value="{{timezone.value}}" *ngFor="let timezone of timezones.success">
              {{timezone.name}}
            </option>
  </select>
 </div>